Metal-oxide-semiconductor (MOS) transistor is one of the most important components in modern integrated circuits (ICs). A basic structure of a MOS transistor includes a semiconductor substrate, a gate structure formed on the surface of the semiconductor substrate, and doped source/drain regions formed in the semiconductor substrate on the two sides of the gate structure. Usually, the gate structure includes a gate dielectric layer formed on the surface of the semiconductor substrate and a gate electrode layer formed on the surface of the gate dielectric layer.
With continuous development of semiconductor technology, traditional planar MOS transistor exhibits weak controllability on the channel current, causing severe leakage current issues. Fin field-effect-transistor (Fin-FET) is an emerging multi-gate device to overcome the problems seen in traditional planar MOS transistors. A Fin-FET usually includes a semiconductor substrate, a fin structure protruding from the surface of the semiconductor substrate, a gate structure covering a portion of the top and the sidewall surfaces of the fin structure, and source/drain doped regions formed in the fin structure on the two sides of the gate structure.
However, for semiconductor devices formed by existing Fin-FETs, the fin structures may still not have a uniform width and the lack of fin width consistency may further affect the performance of the semiconductor devices. The disclosed semiconductor structures and fabrication methods thereof are directed to solve one or more problems set forth above and other problems in the art.